MODULATION OF PLANETARY WAVES IN THE STRATO- AND TROPOSPHERE BY SOLAR ACTIVITY FLUCTUATIONS DUE TO SOLAR ROTATION

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Besides the possible impact of the solar sunspot cycle on climate and weather the modulation of
atmospheric processes by solar emission fluctuations due to the rotation of the sun is a prominent issue of
studies of the impact of solar variability on the atmosphere. Though solar rotation effects are considered
to be less efficient than solar cycle effects, they are nevertheless an important feature to be studied for
mainly two reasons. Firstly, the rotation period of 27.3 days is short enough for statistical analyses of
atmospheric time series where tests of significance have to be performed. Secondly, rotationally induced
fluctuations of solar activity exhibit spectral maxima near 27 days and its first two higher harmonics and
correspond thus to prominent periodicities of the planetary wave spectrum. This fact suggests itself that
planetary waves with periods of about 27 days and less might be sensitive to solar activity fluctuations
due to solar rotation and that their investigation might provide clues to the controversially debated
mechanisms of sun weather relationships. It has also been speculated that the solar cycle impact on
climate might be governed by planetary wave modulation which is itself modulated by the solar cycle.